With increasing age there is a decrease in T cell immune response and an increase in certain disease states, specifically, cancer, autoimmunity, and infectious diseases. It has not been proven, however, that the decrease in immune responsiveness is the cause of the increase in these diseases. In order to further investigate the decrease in T cell immunity, the mechanism must be established. The proposed study will begin evaluation of the role of lymphokines in this decreased response. Specifically, these studies will: 1) determine the amount of interleukin 1 (IL-1), interleukin 2 (IL-2) and interferon (IFN) produced by elderly cells during mitogen responses; and 2) modify the levels of IL-1, IL-2, and IFN present to determine whether abnormalities of these factors are responsible for the observed decreases. The study will evaluate large numbers of elderly (greater than 100) to obtain information reflective of elderly, in general, rather than of a selected population. The information gained in this pilot study will allow future in-depth investigations of the mechanisms of the decline in immune response with increasing age.